The present invention relates to door assemblies of the type where there are multiple doors, at least one of which is mounted to slide along a header on a track to move from an overlapping/compact configuration to an extended position. More particularly, it relates to such assemblies where the doors can also be pivoted as a unit to provide even greater access through the entry after they have been overlapped.
Slidable door assemblies are often used to close off large entries such as entrances to big-box stores or entrances to emergency rooms. In many such applications it is desirable that the doors be fully supported without using a lower rail across the entry. If a shopping cart, forklift truck carrying pallets, hospital gurney, or even just a human is passing through such an entry it is highly desirable for them not to have to pass over any bump or other impediment. Hence, many door assemblies for such applications do not have a lower support rail.
When two-door or three-door assemblies have their doors overlapped to one side of the entry the doors still take up a considerable portion of the opening (e.g. 50 percent in a two-door assembly; about 35 percent in a three-door assembly). Some big-box stores address this problem by having the doors open in opposite directions and when they do so they pass behind walls at opposite sides of the entry. However, this requires there to be sufficient room at the sides of the entry for this to occur.
In some applications there is not enough adjacent wall space available for this. Hence, door assemblies have been designed where such doors are first overlapped at a side of the entry, and then pivoted so as to essentially completely expose the opening. For example U.S. Pat. No. 4,619,074 disclosed a convertible door system that allows the slidable doors to breakout of the supporting upper and lower tracks and to pivot away from the opening. However, the conversion from sliding to pivoting in this design required the extra step of manually moving of a lever.
Similarly, NABCO Entrances, Inc. produced a line of system doors which allowed two doors to slide into overlapping position relative to a pivot only door, and then permitted all three doors to be swung open. However, again, this line also required a separate non-automatic converting adjustment prior to the pivoting.
While these prior art door assemblies sufficed for many uses, to be used quickly and efficiently they required some training regarding how to make the conversion. For example, the employees on duty needed to know how to make the conversion from the sliding motion to the pivoting motion. Some customers prefer not to have to provide such training, particularly where there is likely to be a significant turnover in personnel over time or a large number of persons who may have responsibility for making the conversion.
Moreover, even with properly trained personnel a requirement for a manual conversion step requires some time to achieve it. Some customers, particularly those in an emergency room environment, may prefer to save that time by having a more automated conversion.
In another prior art approach there was a line of door systems which allowed two doors to slide into overlapping position relative to a pivot only door, and then permitted all three doors to be swung open without manual conversion adjustment of a mechanism prior to the pivoting. However, the mechanism to achieve this was in the upper header rail, was somewhat complex (and thus costly to produce), and in some constructions was somewhat susceptible to derailing if not properly used.
Hence, a need continues to exist for improved door assemblies, particularly those which both slide and pivot in a reliable manner without requiring non-automatic conversion adjustments.